Maintenance of the hair consists of washing, conditioning, and styling hair on a regular basis. Traditionally this has been a three step process. Shampoo is first used to cleanse the hair. After the hair is rinsed clean, a second conditioning product is applied and allowed to penetrate the hair for a specified period of time. These conditioning products usually contain cationic conditioning agents which remain bound to the hair fiber after the conditioner is rinsed out. The cationic agents form an insulating coat on the hair shaft resulting in hair with enhanced shine and combability. The third, optional step involves applying a styling aid to the clean hair to assist in arranging the hair into the desired configuration. Many different styling aids are available, including gel, mousse, hairspray, etc.
Within the last decade, cosmetics companies have focused on introducing products which perform more than one function. For example, shampoos are now available which cleanse and condition the hair in one step, thus eliminating the need for two separate products and two separate applications. The popular two-in-one shampoos are formulated with three essential ingredients besides water: an anionic surfactant, an insoluble nonvolatile silicone, and a suspending agent for the silicone. The silicones deposit on the hair to form a protective film which makes the hair softer, and improves combability and sheen. These shampoos do have certain disadvantages. The insoluble silicone, by reducing the inter-fiber frictional forces, reduces the ability of the hair to hold a curl. In addition, habitual use of these two-in-one shampoos causes a silicone film to build up on the hair. This silicone film is known to interfere with the effectiveness of other hair treatment procedures such as perming, coloring, or straightening. Although these two-in-one shampoos are very popular, their inherent disadvantages make it desireable to formulate shampoos which provide two-in-one conditioning without sacrificing the effectiveness of styling, perming, coloring or straightening treatments.
Other types of two-in-one shampoos achieve conditioning effects with cationic conditioning polymers rather than silicones. However, the incompatibility between cationic hair conditioning polymers and anionic surfactants is well known in the art, so shampoos which achieve conditioning by the incorporation of cationic polymers often use nonionic or amphoteric surfactants instead of the traditional anionic surfactants. The resulting shampoos are less than desireable for commercial purposes because anionic surfactants generally produce copious foam while nonionic and amphoteric surfactants do not. In reality there is no positive correlation between the amount of foam a shampoo produces and the degree to which it cleanses. Unfortunately, however, consumers equate foaming with cleansing, and shampoos which do not foam well are perceived to be less effective in cleansing performance.
Other types of dual function shampoos which provide cleansing and hair setting features are known. These shampoos contain some of the hair setting resins traditionally found in styling aids, the end result being a shampoo which cleanses and provides a subtle, temporary set to the hair after shampooing. In particular, U.S. Pat. No. 5,118,498 to Helioff, discloses hair setting shampoo compositions which contain anionic surfactants, water, and an alcoholic solution of the ethyl butyl alkyl half ester of a C.sub.1-5 alkyl vinyl ether maleic anhydride copolymer. This resin is known by the trade name "Gantrez". Most hair setting polymers have relatively low water solubility so they are either sold in a solvent solution which, when added to the shampoo composition enhances solubility, or, in the alternative, solvents must be added to the shampoo composition to facilitate solubility of the hair setting polymers. There are many disadvantages to putting solvents such as alcohol into shampoo compositions. Most solvents are foam depressants and tend to be drying to the hair. Because of consumer perceptions foam quantity is an important factor in commercial success of shampoos. Second, hair setting resins which are supplied in alcohol are more expensive than resins which are supplied in the powder form or dissolved in water.
For the above reasons it is of interest to formulate three in one shampoos which cleanse, condition, and provide a subtle set to the hair in one step, and at the same time are free of nonaqueous solvents. It is essential that these shampoos provide comparable if not superior cleansing, conditioning, and styling properties without the disadvantages of the prior art products.